Marine Biodiversity was the theme for International Day for Biological Diversity (IDB) in 2012. Designation of IDB 2012 on the theme of marine ecosystems provides Parties to the Convention on Biological Diversity (CBD) and everyone interested in marine life, the opportunity to raise awareness of the issue and increase practical action.

How Much Life Is in the Sea?

From 2000 to 2010, an unprecedented worldwide collaboration by scientists around the world set out to try and determine how much life is in the sea.

Dubbed the ‘Census of Marine Life’, the effort involved 2,700 scientists from over 80 nations, who participated in 540 expeditions around the world. They studied surface seawater and probed the deepest, darkest depths of the ocean, sailed tropical seas and explored ice-strewn oceans in the Arctic and Antarctic.

By the time the Census ended, it had added 1,200 species to the known roster of life in the sea; scientists are still working their way through another 5,000 specimens to determine whether they are also newly-discovered species. The estimate of the number of known marine species - the species that have been identified and the ones that have been documented but await classification - has increased as a direct result of the Census efforts, and is now around 250,000. (This total does not include some microbial life forms such as marine viruses.) In its final report, the Census team suggested it could be at least a million. Some think the figure could be twice as high.

The Human Impact

For many coastal peoples, the sea is rich in meaning and spirituality, religiously significant and central to their very being. The legends and traditions of the Maori of New Zealand feature fishing heavily, with one tale positing that the country was discovered by the great explorer Kupe while hunting a giant octopus. Traditional coastal whalers in Japan maintained Shinto whale shrines and whale temples, where detailed descriptions of the whales and their deaths were maintained. For the Inupiat of Alaska, the hunting of the bowhead whale remains to this day more than a form of acquiring food, but is instead the fundamental act around which every aspect of their society, and indeed the very purpose of their existence, revolves.

However, the human presence on and near the ocean has not always been to the ocean’s benefit. Because of over-hunting, gray whales are no longer found in the Atlantic and are close to disappearing from the western Pacific; in the Atlantic Arctic, bowhead whales number in the hundreds at most. In the Southern Hemisphere, where once there were perhaps 200,000 blue whales, there are now maybe 1,000. The great auk, sea mink, Steller’s sea cow and Caribbean monk seal are all extinct.

Today, the vaquita, a porpoise found only in the Gulf of California, may number as few as 100 individuals. The southern bluefin tuna and elkhorn coral are critically endangered, as are several species of sea turtles. Hammerhead, thresher and white sharks have declined in the Northwest Atlantic by more than 75 percent in 15 years; in the Mediterranean Sea, sharks have declined 99.99 percent from historical abundances in the early nineteenth to mid-twentieth centuries.

Since 1980, an area of seagrass meadow the size of a soccer pitch has been lost every 30 minutes, and almost 30 percent of all seagrass beds are estimated to have been lost. Similarly, about 35 percent of both mangroves and coral reefs worldwide are believed to have been damaged or destroyed as a result of human activities - a figure that does not take into account the growing impacts of climate change.